<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      span {
        /* width: 20px; */
        display: block;
        /* border: 10px solid #f00; */
        background-color: #f00;
        border-radius: 50%;
        font-size: 20px;
        color: #fff;
        text-align: center;
      }
    </style>
  </head>
  <body>
    <span>1</span>
  </body>
</html>
